1. Field of the Invention
This invention relates to test stands, and more particularly to test stands for calibrating seed meters of vacuum and mechanical types.
2. Description of the Related Art
Test stands for calibrating contemporary vacuum and mechanical seed meters are well known in the art. These stands comprise structure for supporting an endless belt with ears for forming seed cells, and with the upper horizontal level of the belt being sufficiently long to show to the naked eye approximately fifty one inch (1") long cells, and with mechanism for moving the belt at speeds simulating the ground speed of the planter carrying the seed meter.
Mounted above one end of the belt may be either one meter or two placed side-by-side, and placed above the belt such as to drop by gravity seeds from a meter onto the belt. As two basic types of seed meters are used by farmer operators each as an element of a seed planter apparatus attached to and pulled behind a prime mover such as a tractor; one being of a mechanical type in which mechanically actuated fingers or similar mechanical devices are typically used to separate individual seeds from a seed mass fed to the meter, and then dispense them sequentially into a furrow, and the other being an air-type meter in which a rotating element coupled to a source of air pressure or vacuum picks up seeds from a seed mass fed to that meter for subsequent sequential, individual discharge from the meter as the element continuously rotates, contemporary test stands usually provide for the dual mounting.
As with the belt, mechanical mechanism is provided for operating both seed meters, each at a rate identical to that of the belt and again simulating the ground speed of the planter carrying that particular meter, with air mechanism provided additionally for operating the air side of the air meter. For example, the stand may have a digital readout for showing the mph rate of speed being applied to each meter and to the belt, and may also have a monitor showing the psi of vacuum applied to a vacuum seed meter. Both the rate of speed and the amount of vacuum are variable, with appropriate controls provided as part of the test stand, to simulate actual planter operation in the field.
It should be noted that the function of a seed meter, regardless of type, is to drop single seeds sequentially regardless of the size of the seed, or the weight or shape of the seed, and at times at relatively high rates of speed. For example, some farmers try to make their meters drop over 22 seeds per second in the furrow, an incredible feat. The importance of such "singulation", however, becomes readily apparent when it is realized that proper spacing of seeds in the furrow is an important factor in achieving the best yields. Improper spacing of seeds in the form of skips, doubles or triples (dropped at the same time), has been shown to result in too quick of a cross-over of seed roots, creating a competition of the plants for the soil nutrients, all of which unfavorably affects the maturity of the plants and the resulting yield.
Thus, calibration of a seed meter to attempt to achieve the drop of a single seed into each single belt cell, simulating a proper spaced dropping of single seeds in a trough in the field, is a worthy achievement.
Contemporary test stands have been found wanting in several areas. The seed meters are mounted too high above the belt for the purpose of utilizing elongated, curved seed tubes, with the tubes utilizing an electronic sensor which counts the population of seed being discharged from the meter. However, knowing the total seed drop doesn't necessarily indicate the types of errors. For example, testing a seed meter by population alone does not show the true nature of the seed drops. Five percent skips and five percent doubles averages out to a 100% drop. To the elimination of the use of a seed tube with population counted to achieve a more accurate indication of the efficiency of a seed meter, and to a correction of any error indication while on the test stand is one goal of this invention.
It has also been noted that the belt is under sufficient tension that seeds tend to bounce a sufficient height or direction, such as to bounce out of a cell as the cell pauses below the seed meter discharge chute. Further, the inherent nature of a mechanical seed meter discharge chute enhances seed deflection and bouncing to again cause doubles or triples to show on the belt, misleading the operator when actually the calibration is correct.
Another needed improvement stems from the required placement of a vacuum seed meter on the contemporary stand such that an opening formed in a cover of the meter faces the rear of the stand, the opening permitting a viewer to view seeds as they are held within air pockets or cells to a rotating disk. The operator of the stand, normally working in front of the stand with the controls at the front, finds it virtually impossible to utilize this asset of the seed meter as an aid to calibration.
To removal of these disadvantages of the contemporary seed meter test stand, the instant test stand is dedicated.